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"Big Plossls" - Televue 55mm, Meade 4000 56mm, ...

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#1 mloffland

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Posted 22 December 2009 - 04:37 PM

"Big Plossls" - Televue 55mm, Meade 4000 56mm (4-Element Design), Meade 4000 56mm (5-Element Design)

#2 plyscope

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Posted 22 December 2009 - 10:01 PM

Another great review Bill, thank you.

As you may recall I asked about 50-56mm eyepieces in a thread some time ago and you referred me to another previous article. I ended up buying a new Tele Vue 55mm.

I was tempted by the Takahashi 50mm LE after hearing positive comments but in the end the TV 55 was a lot less expensive and has a slightly larger true field of view which was my main reason for this size of eyepiece in the first place. I have not had much use from it yet but I like it so far. The threaded adjustable eyeguard is a useful feature.

The only other eyepiece I have tried in this range is the GSO 50mm Superview. It was very inexpensive but I found the eye relief excessive and eye placement difficult. I sold it in preference to a 40mm GSO reverse kellner. I can at least say that I like the TV 55 much more than that. I would like to see Tele Vue release a 42mm plossl with a 2 inch barrel and 50 degree apparent field. The 40mm 1.25 inch eyepiece would still be cheaper and have it's own somewhat limited market. My 2 cents. :)

#3 John Rhodes

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Posted 30 December 2009 - 04:14 PM

I'd just like to clarify a couple of comments made in the "Big Plossls"
review. First it was mentioned that the Tele Vue 55mm Plossl was made in
China. That is not true. All Tele Vue eyepieces are made solely in Japan
and Taiwan to Tele Vue's design, Japanese glass material, and tolerance
specifications, with final inspection is done at Tele Vue in Chester, NY.

Secondly, it was mentioned that using an exit pupil larger than the
observer's eye pupil would create a "much dimmer image." This is not
correct. The image will be exactly as bright as an eyepiece that produces
an exit pupil that matches the observer's pupil since the limiting factor is
observer's pupil diameter. This is was well covered by Al Nagler in his
tutorial "Telescope Formulas, Common Telescope Myths" see Myth #2
http://televue.com/e...page.asp?ID=141

#4 deSitter

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Posted 04 January 2010 - 02:20 AM

I have not had the opportunity to use the 5-element Meade or Televue but I do own the 4000 4-element. It's a big simple wonderful thing - nothing fancy. It does have a role it fills perfectly - it's the default occultation eyepiece along with the 5" f/9.3 refractor she's most comfortable with. The framing of the Moon and a soon-to-be-occulted star or several, is just perfect. Stopping down the scope to f/14 produces a 4mm exit pupil with perfect definition and little color all over the field. The other two may be better but I doubt I could see it in this application. This combo at full aperture produces a maximum-sized exit pupil and makes a wonderful star field sweeper.

For the price, unbeatable.

-drl

#5 Live_Steam_Mad

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Posted 29 April 2014 - 01:48 AM

Odd how quite a few online sellers specify the Eye Relief of the Meade 56mm Plossl at 21mm (can't be true, surely?!) whereas TeleVue specifies 38mm Eye Relief for their 55mm Plossl.

What is the real Eye Relief of the Meade 56mm Plossl 4 element design, and what is the real Eye Relief of the Meade 56mm Plossl 5 element design?

If no one has the actual figure, can someone who has either one please estimate it for me? I am a spectacles wearer.

Regards,

Alistair G.

#6 alnitak22

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Posted 29 April 2014 - 05:53 AM

I'd just like to clarify a couple of comments made in the "Big Plossls"
review. First it was mentioned that the Tele Vue 55mm Plossl was made in
China. That is not true. All Tele Vue eyepieces are made solely in Japan
and Taiwan to Tele Vue's design, Japanese glass material, and tolerance
specifications, with final inspection is done at Tele Vue in Chester, NY.

Secondly, it was mentioned that using an exit pupil larger than the
observer's eye pupil would create a "much dimmer image." This is not
correct. The image will be exactly as bright as an eyepiece that produces
an exit pupil that matches the observer's pupil since the limiting factor is
observer's pupil diameter. This is was well covered by Al Nagler in his
tutorial "Telescope Formulas, Common Telescope Myths" see Myth #2
http://televue.com/e...page.asp?ID=141


Thank you, John, for the corrections. I continue to be amazed at the erroneous info that is claimed as fact in online "reviews." One would think that by now no one could be under the impression that Tele Vue gear is made in China. And Uncle Al's article that you cite has been available for years. Stating one's preference for an eyepiece is subjective. Presenting incorrect information is not subjective. I hope Mr. Paolini amends his article to address this.

#7 Live_Steam_Mad

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Posted 23 May 2014 - 12:20 AM

Can someone who has either the 4 element or 5 element Meade 56mm Plossl please tell me whether their spectacles ever come into contact with the surface of the eye lens at all, when the rubber eye cup (if there is one) has been removed? Reading glasses would be a way to test also.

I wear frameless plastic lens glasses and they come into contact with the eye lens on my 28mm SkyWatcher Kellner (56 degree FOV, very good eye relief, easy to see all the field with my glasses on) and my also on Meade 26mm Super Plossl where I cut down the barrel since the eye relief was terrible and now it's pretty good (can just see all of the field with glasses).

Same question please for the TeleVue 55mm Plossl when the screw on eyeguard and rubber eye cup has been removed.

In comparison for example my 8mm TeleVue Radian's eye lens has never come into contact with my glasses, nor has my TeleVue 32mm Plossl or my Meade 25mm Modified Achromat (all with rubber eyeguards removed to gain eye relief).

If all the manufacurers used the screw up / down eyeguard like Pentax uses on their XL's then we would all have the ability to adjust it in an infinitely variable manner so that we never brush the eye lens with our eye lashes or smear grease from our spectacles plastic lenses onto our eye lenses.

BTW can someone take a picture of the TV 55mm Plossl with the upper eye guard removed?

Best Regards,

Alistair G.

#8 TONGKW

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Posted 26 May 2014 - 05:06 AM

I have a Meade 56 mm eyepiece (4-element design). The eye relief is not that long at just over 20 mm by my reckoning as I can just see all the field wearing my spectacles. The specified 21 mm eye relief appears to be right.
There is no way my spectacles could come into contact with the surface of the eye lens of the eyepiece, even with the rubber eye cup off, as the lens element is deeply recessed.
http://www.optcorp.c...eyepiece-2.html

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#9 jrbarnett

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Posted 26 May 2014 - 11:57 AM

Meade is no doubt measuring the ER from the upper edge of the housing, rather than the eye lens. The eye lens is very deeply recessed into the housing on the Meade, whereas the Televue's eye lens isn't far below the rubber eye cup.

- Jim

#10 Live_Steam_Mad

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Posted 31 August 2014 - 07:52 PM

Meade is no doubt measuring the ER from the upper edge of the housing, rather than the eye lens. The eye lens is very deeply recessed into the housing on the Meade, whereas the Televue's eye lens isn't far below the rubber eye cup.

- Jim

 

Yes, I found out that the Meade 4000 56mm 4 element made in China ep has a large, removable metal eye cup and that when you screw it off you expose the approx. 2" diameter eye lens ;-

 

http://astronomer.pr...yepieces?page=1

 

...so the actual ER could well be 21mm when the metal eyecup is screwed on, and the design ER (from eye lens top surface to eye ball's eye lens top surface) maybe similar to the TeleVue 55mm at 38mm or so. I can see now that the TeleVue 55mm PL has a design ER of 38mm but because it also has a screw on metal eye cup it has a lower actual ER in practice when using it with the metal eye cup in place.

 

BTW I was also interested to see if the Meade 4K 56mm 4-element made in China ep had a sharp, black field stop (edge to the circle of light that you see when you hold it to your eye with no telescope and no diagonal present). Someone answered on Amazon when I asked this question specifically about this exact ep and I was told that it does have a sharp field stop ;-

 

http://smile.amazon....ords=meade 56mm

 

(see questions and answers section on that page).

 

Also I noticed that e.g. when I view U Cygni (the only star that I ever saw that was blood red) in my C11 SCT, more magnification reduced the red color instead of increasing the contrast on the red color with the background sky, which suprised me. I think it's to do with needing the largest possible exit pupil which maximises the eye sensitivity to colors in the "dark". So I think I'd like to try this ep. instead of e.g. Vixen 42mm LVW 72 degree ep which has just a little more TFOV but more magnification.

 

I see that the 4K Meade 56mm ep. is sold out nearly everywhere now.

 

One last thing concerning the above that I wrote, when I was talking about the plastic lens of my spectacles coming into contact with the eye lens of the eyepieces I was not taking about the Eye Relief, I was referring to whether my spectacle lens literally contacts the glass of the eyepiece.

 

Turning to actual ER, and considering whether I can see the whole FOV whilst wearing glasses, with my SkyWatcher 28mm 56° 2" Kellner (no ER specified) I hardly ever bump into the eyepiece with glasses on (when I remove the rubber eye cup) but with my Meade 4K 26mm SP even when I cut down it's eye lens side black metal barrel to shorten it and change it to about 20mm ER for glasses wearers, the ER was still not enough and I do bump into it a lot with glasses on, also happens with my TeleVue 32mm Plossl (22mm ER) that I bump into a lot with glasses on even with the rubber eye cup removed, and same with my TeleVue 8mm Radian with it's 20mm ER even with it's rubber eye cup removed, I still bump into it a lot with glasses on. I can fortunately see the whole FOV with glasses on with these four eyepieces, but I wish they all had a little more ER.

 

Best Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 01 September 2014 - 09:58 PM.


#11 LivingNDixie

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Posted 01 September 2014 - 12:15 PM

Alistair,

 

Generally lower powers are best for colorful stars such as carbon stars, at least the brighter ones. Also aperture can make a difference with smaller scopes seeing better color then larger ones.



#12 Live_Steam_Mad

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Posted 01 September 2014 - 07:39 PM

Can someone here who has one tell me if this Meade 4K 56mm 4-element made in China ep has a sharp, black field stop (edge to the circle of light that you see when you hold it to your eye with no telescope and no diagonal and no extension tube(s) present) ?

 

For example I read that the TeleVue 55mm Plossl "has no field stop", but to me it sounds like it is simply vignetting at the edges when used with the person's diagonal / extension tube / scope.

 

For example, I have a TV 32mm Plossl (bought new by me in 2012 approx) with a sharp black field stop, however when I put it in my C11 I find the eye lens height a little too low, so I end up unscrewing the bottom of my Barlow lens part from my Relevation (GSO) Barlow and then I use the Barlow tube as an extension tube which brings the ep to the correct height, BUT the tube has a restricted opening to accept the Barlow lens element section, which causes the 32mm PL to vignette around the edges and create a "blurred" field stop "inside the original field stop" (I can still see the original field stop if I look carefully).

 

I think what is happening to with their 55mm PL is something like e.g. their SCT adapter ring on their C9.25" or even their C11 (the 3.25" to 2" step down part, like mine) has an opening (of 38.3mm internal diameter) which is less than the 55mm's 46mm field stop and is causing a blurred edge to appear? (which also means that the C8 would have this problem with it's mere 38mm opening as a maximum, same as the primary baffle tube diameter, nothing can be done about it, so would need C11 / C14 to use 55 / 56mm Plossls or other wide TFOV ep's like 41mm @68 degrees or 31mm @ 88 degrees etc. and not vignette and cause an artificial blurred "field stop"). The diagonal can also cause vignetting too I suppose, if it's not got quite a large enough opening. Fortunately at least I have a Revelation / GSO 2" diagonal with 46.5mm minimum opening on the eyepiece side 2" tube ;-

 

https://plus.google....0273?banner=pwa

 

...and this diagonal is the only one on the market with interchangeable SCT or 2" refractor style tubes on the telescope side (I bought the SCT version of the diagonal then also bought the GSO 2" Chrome barrel for refractors for it also and thus now I have a diagonal that can fit either SCT's or refractors with no visual back needed.

 

So the only real way of confirming this is for me to ask, if the Meade 56mm (any of the versions) or TV 55mm have a sharp black edge to the circle of light that you see when you look through the ep with NO 'scope and NO diagonal and NO spacer tube(s)?

 

BTW you can get a clear 2" aperture on C11 and C14 by using the Astro Physics 2" Visual Back for Celestron 11" & 14", or "Baader 2" Clicklock Adapter for 3.25" SCT's". You can also get the AP one for Meade 10", 12" and 14" SCT's, so you have to make sure to get either the Celestron 3.25" or Meade 3.25" thread as needed! They use slightly different threads!

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 01 September 2014 - 10:12 PM.


#13 Live_Steam_Mad

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Posted 01 September 2014 - 07:42 PM

Alistair,

 

Generally lower powers are best for colorful stars such as carbon stars, at least the brighter ones. Also aperture can make a difference with smaller scopes seeing better color then larger ones.

 

Thanks, yes I noticed lowest magnification seems to give largest amount of color, always. I have however never seen that latter situation that you mention. All the larger 'scopes that I have ever looked through show more color, never less, than small 'scopes. That's one of the reasons I bought the C11 (and it's the most 'scope that I can handle for one person and on the only mount that I could afford (CG-5).

 

Regards,

 

Alistair G.



#14 Live_Steam_Mad

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Posted 01 September 2014 - 09:23 PM

OK here's what additional info I found so far, nevy tells me that the Meade 56mm "Smoothie" Plossl (5 element, Japan) has "plenty" of ER, it's "very clear to the field stop" by which I took to mean has a sharp field stop. hottr6 tells me about this same exact ep "ER on this puppy is way more than 25mm... maybe 35+mm. I'll have to measure it [ ], and yes, the field stop is very well presented." Gord told me also about this same exact ep "I don't believe I know what the exact eye relief is on it in terms of an exact number. I just know that it is very long. I don't wear glasses, and there are times I find it almost too long for me. I actually prefer tight ER in the 10-15mm range [ ]. As for the field stop, yes, this one has a very sharp, distinct cut-off. I know what you mean about some not being so."

 

So I take the Eye Relief on the Meade Series 4000 56mm 5 element made in Japan "Smooth Sided" Super Plossl to be about 35mm, and I take this same exact ep to have a sharp, black field stop. The 35mm ER seems a bit too long for me, even though I wear glasses, so I think I will go with the 4 element much cheaper version that has around 21mm ER according to the official figures on the Meade webpage for the Series 4000 4-element Super Plossl which is made in China.

 

I still would like to hear from any and all who have the Meade 4K 56mm 4-element made in China and can tell me whether it has a sharp, black field stop (edge to the circle of light that you see when you hold it to your eye with no telescope and no diagonal and no extension tube(s) present) ? And as to whether they end up bumping / rubbing their glasses against the rubber eye cup (or if they remove the rubber eye guard at all like I tend to do on my ep's) on this exact ep.

 

Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 01 September 2014 - 10:15 PM.


#15 areyoukiddingme

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Posted 21 September 2014 - 12:55 AM

I have the Televue 55 plossl, and I always have a fuzzy edge to the FOV. Doesn't matter what scope I used. Televue 101, 12.5" Portaball; 11" Edgehd; 16" Lightbridge; and 80mm Orion triplet.

 

I did just unscrew the lens cover to see if that was the culprit. Nope. Still there, perhaps a touch better. Then for the hell of it, I unscrewed the eyepiece and removed the lens elements. I can see no way to get rid of the vignetting effect.



#16 Live_Steam_Mad

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Posted 21 September 2014 - 03:31 PM

I have the Televue 55 plossl, and I always have a fuzzy edge to the FOV. Doesn't matter what scope I used. Televue 101, 12.5" Portaball; 11" Edgehd; 16" Lightbridge; and 80mm Orion triplet.

 

I did just unscrew the lens cover to see if that was the culprit. Nope. Still there, perhaps a touch better. Then for the hell of it, I unscrewed the eyepiece and removed the lens elements. I can see no way to get rid of the vignetting effect.

 

So you are saying that the TV 55mm Plossl has a soft, blurred field stop ("vignetted", or "no field stop") even when just held up to the light, when intact, with or without the screw-on metal eyecup, and without putting it into ANY additional equipment such as telescope / diagonal / barlow / extension tube etc. ?

 

Interesting. I also read that the Panoptic 41mm has this same problem of blurred field stop no matter what scope it's used in. But noone told me yet whether the Pan 41 has a blurred field stop when just held up to the light, either with or without it's screw on metal eyeguard. I prefer ep's with sharp black field stops.

 

The Meade 4K 56mm 4 element is not in stock anywhere now except Amazon Japan (who have several of them, but the price is very high!). Unless someone can find it in stock elsewhere and wants to let us know?

 

Best Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 21 September 2014 - 03:33 PM.


#17 Live_Steam_Mad

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Posted 17 October 2014 - 02:53 AM

I managed to buy the Meade Series 4000 56mm 4-element Made In China Super Plossl, it arrived this week. The first thing that I noticed when I looked through it with my glasses on was that I could not see the edge of the AFOV. So I removed the rubber eye cup from the ep and I have never used the eyecup since. Even without the rubber eyecup I could see that there was considerably less Eye Relief (IMHO) than the 21mm figure that I have seen mentioned, when I was wearing my glasses.

 

For example, I can see the entire FOV of my TeleVue 32mm Plossl (22mm design ER) and TeleVue Radian (20mm design ER) and SkyWatcher 2" 56° Kellner all with glasses on. But I cannot see the whole FOV of this Meade 56mm even with spectacles pressed as far into my face as I can. I instead see about 82 to 85 per cent approx. of the AFOV. I cannot see the remaining 15 to 18 per cent, which leaves me seeing a blurred edge to the circle of light, with my glasses on. This is with the rubber eyecup removed.

 

If I remove my glasses, with rubber eyecup removed also, I see a lovely sharp black field stop on this 56mm ep (this is without having the ep in any scope / diagonal / barlow etc, just instead held up to the lit up walls in a room) since I gain significant ER by removing my glasses. BUT I really have to PUSH my eye into the eyepiece to see it (this being with glasses OFF), unlike with my other eyepieces. Even with my glasses removed and my severe astigmatism in my own eyes, I can see that the field stop is satisfactorily sharp. I then noticed some kind of sharp black foreign material on the edge of the AFOV field stop circle, which annoyed me. I shone a VERY bright Tesco brand torch (flashlight) with single LED (the kind that can light up a house at 100 feet) at the lenses but could not see anything odd. Then I realised that the field stop might not be internal but might be the metal barrel at the bottom of the eyepiece.

 

So I unscrewed the barrel off the end and the lenses stayed put and I could see a metal retaining ring now where the barrel had been, for keeping the lower lens group from falling out. And indeed I was right, the view with no spectacles on now had a blurred edge with rather larger AFOV. So the barrel itself is the field stop. You can see this by screwing the barrel back on whilst looking through the ep at the same time! You can also see a blurred finger nail entering the FOV if you so much as poke your finger more than 1mm into the light path. The bottom of the barrel is not the field stop, instead a ridge / rim some distance from the very bottom of the metal barrel, but still part of the unscrewed metal barrel, acts as the field stop, not anything at the edge of or inbetween the lenses.

 

I then examined the unscrewed metal barrel and low and behold there were 2 small nicks / bad machining in about a 4mm length at one point around this inside "ridge" or rim inside the barrel, some distance inward from the very bottom of the barrel, as mentioned. So I took a curved fine teeth file and took the edges off this small bad section and presto! the sharp black field stop was perfect. Another small detail that Meade could not be bothered to do any quality control on. Oh well, it's sorted now.

 

I must say I was impressed by the general quality of the contruction of the ep though, the anodising and machining of the upper section was very good with only one small nick on the very top rim where the eye cup had been, but I suppose I can accept that. I noticed that one letter of the "Super" wording of the yellow text around the top of the ep. was not applied quite properly and I was slightly irked by it LOL. The bottom chrome barrel has no indent for retaining thumbscrews and the chrome / nickel plating was very well done.

 

The lenses both top and bottom appear to be Magnesium Flouride (MgFl) coated, NOT multicoated, despite the wording on the ep. The reflections from them under fairly bright room lighting were yellow and blue / purple, instead of the green that my Meade 26mm SP showed.

 

I tried (just for fun) to unscrew the top section off the 56mm ep but despite my most inensive efforts it won't unscrew. At some point I will probably cut (!) the very top part of this upper section off (the part that retains the useless rubber eye cup that I have no want or need of, being a glasses wearer) in order to gain a last few mm of Eye Relief and finally I might be able to actually see all of the AFOV with my glasses on.

 

I noticed that there seemed to be very little if any sensitivity to eye placement, or kidney beaning (Spherical Aberration of the Exit Pupil) when just viewing through the ep without glasses and then with glasses whilst just holding the ep up to the light. HOWEVER once I actually tried the ep in my 4" F8 Achromat (Meade SN102), I started to get rather bad SA of the exit pupil and eye positioning became VERY sensitive, with my glasses OFF, this being when I tried to push my eye in far enough to see the whole AFOV at once, but at least I get a sharp black field edge when viewing with the ep through the scope with glasses off. However, with glasses on, I am backed off from it enough that there is no sensitivity to eye placement, and no SA of the exit pupil, but the edge of the AFOV is blurred as I cannot get far enough in to see the edge of the AFOV.

 

I have the feeling that if I cut down the top of the ep a little then I would gain ER and see more of the AFOV with glasses on, but I suspect I might start to get some SA of the exit pupil / eye placement sensitivity also. BTW the SA and eye sensitivity effects with glasses off were much greater with this 56mm ep in my 4" scope compared to my 32mm Televue Plossl or even my Meade 26mm S. Plossl 4K series where I cut down the barrel on the eye end to gain ER so that I can see all of the FOV at once with glasses on, this latter ep shows almost no sensitivity to eye placment or SA of the exit pupil even with my glasses touching the eye lens of the ep.

 

Performance on the 4" F8 Achromat indoors viewing textiles at 25 feet distance was very good indeed through this 56mm ep. Very sharp, no false color at any aperture (I use aperture masks of various sizes to test with), beautiful high contrast and intense colors. However with a Hubble artificial star, the views ranged from extremely sharp Airy Disc (smallest one used, at 8mm aperture being tested (!) which gave me 16x magnification with 0.5mm Exit Pupil, needed because I have severe Astigmatism in my own eyes that my glasses can't fully correct for but that does only show up when I get over 0.8mm or so exit pupil) to very obvious astigmatic crosses (to be expected, when tested at full 100mm aperture, same 16x magnification but large 6mm exit pupil which shows up all the defects in my own eye lens of my own eyes).

 

Off axis performance was very good indeed, the 4" F8 Achro has a pretty flat field and Airy discs from my artifical star (smallest Airy disc of the 5 on the Hubble AS) remained unaltered in appearance until very close to the edge (about 85 to 90 per cent at F8, and of course practically right to the field edge at F100 with 8mm aperture LOL) with this 56mm ep. This walked all over my SKyWatcher 28mm Kellner where stars become distorted very quickly at 50 per cent out and beyond at F8. I tested the off axis performance entirely with glasses ON, so was only testing out to maybe 85 per cent of the AFOV at most, but it can't be helped, as I always wear glasses when observing, and I won't be taking them off to observe with this ep.

 

All things considered then, as long as I wear my glasses to observe, this eyepiece is very good to excellent optically, and I am pleased with it. It's rather heavier and larger in person than I was expecting but nevermind. I tried a quick look through the ep with my Meade 7" Mak and C11 SCT indoors just to see and it looks usable but proper tests with those 'scopes will have to wait until later. I hope the 38mm primary inner baffle of my 7" Mak won't cause too much noticeable vignetting (but then again I don't think I'll notice that much as I am already prevented from seeing the outer 15 to 20 per cent of the AFOV by my glasses and the limited ER that this ep has). I personally would rate this 56mm ep's Eye Relief at more like 16 or 17mm than 21mm.

 

Best Regards,

 

Alistair G.


Edited by Live_Steam_Mad, 17 October 2014 - 03:23 AM.







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